This is an alternative assessment activity in which students pull apart a rotting log as an example of a microhabitat that can be explored in the classroom. As they dissect the log and discover the myriad of bizarre creatures on and inside the log, the notes the students keep can be used as an assessment of many of the major concepts in this unit. Another use for this lab is as an engaging way introduce a very special organism-organism relationship, symbiosis. Termites have a symbiotic relationship with the protozoa in their gut. The protozoa that digest the cellulose in the wood for the termites, can be extracted from the termites’ gut and observed under a microscope. One of my students who witnessed the extraction and then saw the protozoa proclaimed “That was the coolest thing I have ever seen. Ever.” Finally, if you are just fascinated by termites and want to become completely enamoured, try putting a termite on a line drawn by a Bic pen…
Assessment or continued exploration of microhabitats
Groups of 4-6 students per log
For each student:
For each group of students:
Optional: To see the protozoa in the termites’ gut
I used this activity as a lab-based test that the kids didn’t actually think was a test. It was a super way for them to reveal the holes in their understanding before the written test. Some of the major concepts that can be assessed in this lab include differentiating between a community and an ecosystem, creating food webs, identifying interactions between organisms and between organisms and their environment, predicting the effects of human impact on populations, and assessing ecosystem sustainability.
In addition, I was able to show them an amazing symbiotic relationship between termites and protozoa. Termites eat wood but cannot completely digest the wood on their own. Many varieties of protozoa, single celled animals with amazingly varied modes of locomotion, live in the termites hindgut and help digest the cellulose in the wood. They attach themselves to the inner wall of the termite’s gut to keep from being excreted with undigested wood particles. In return for their invaluable services, the protozoa get a nice, safe home and a constant supply of food.
Knowledge of food webs, ecosystems, organism-environment interdependence, and sustainability.
Optional: Set up protozoa viewing station. I would practice extracting protozoa on your own first. The protozoa are active for around 2 hours before they stop moving so you’ll need to set up a new slide every few hours.
- List as many organisms in the ecosystem as you can find. For each organism, draw a picture and label it with a name that describes the organism like “light-brown, long bodied ant-like thing” or “2 cm-long black beetle”. More things are living than you might think…
- List as many non-living parts of the environment as you can find. There is more than just wood – think about solids, liquids AND gases!
- Which of the things you just listed are part of the log community?
- Which of the things you just listed are part of the log ecosystem?
- What is the difference between a community and an ecosystem?
- Find evidence about the food webs that make up the community. Do you see any organisms eating? Do you see any “poop” that gives a hint about what the organisms have been eating? Draw as much of the food web as you can.
- Describe one organism-organism interaction that you observe.
- Describe one organism-environment interaction that you observe.
- How will this lab impact the populations of organisms in your log? Pick one organism and describe how the population of this species will be affected by our investigation.
- Is this ecosystem sustainable? Why or why not? Use your observations to support your idea.
- If you have a protozoa viewing station set up, invite groups one at a time to come visit you at the microscope to see the protozoa.
- Reserve plenty of time to clean up.
Another cool termite trick… Did you know that termites mistake the smell of a Bic pen for a pheromone that they use to navigate? Pheromones are chemicals that communicates a message to other members of the same species. Although humans do have pheromones, termites and other social insects communicate extensively through these chemical messages. Termite workers indicate the path to a food source by leaving behind a trail-pheromone. A chemical in Bic pens (not other pens for some reason) mimics the trail-pheromone. If you draw a line with a Bic pen on paper then place a termite on the line, the termite will faithfully follow the line wherever it leads. Try drawing curly-Qs and other shapes. See what happens when a termite hits a crossroads. Try pens by other manufacturers. Try different colors of Bic pen.
The idea for this activity came from a workshop by Karen Kalamuck at the Exploratorium. THANK YOU Karen!
If you just can’t be bothered to go find rotting logs but really want to try the termite activities, termites can be ordered from Carolina Biological with instructions for how to isolate the protozoa ($11.25) OR with instructions for how to draw lines with Bic pens ($32.75).
Ecology (Life Sciences)
5. Organisms in ecosystems exchange energy and nutrients among themselves and with the environment.
Investigation and Experimentation
7. Scientific progress is made by asking meaningful questions and conducting careful investigations.